JP6997372B2 - Dry etching method and etching equipment - Google Patents

Description

The present invention relates to a technique for etching a metal film using an etching gas containing β-diketone.

In the process of manufacturing a semiconductor device, a metal film formed on a substrate may be etched as a wiring material, a metal gate material, an electrode material, or a magnetic material.

With the miniaturization of semiconductor devices, it is required to highly control the etching of the metal film in order to etch the metal film to form a fine structure. Specifically, the metal film is etched so that the variation in the etching amount is suppressed to 1 nm or less in the plane of the wafer, the roughness of the surface of the metal film after etching is controlled, and the metal film is selectively etched. Things are being considered. In order to perform such advanced etching control, it is difficult to perform wet etching in which a metal film is etched with a chemical solution, and dry etching in which a metal film is etched with a gas has been studied.

For example, in Patent Document 1, a thin film formed on a substrate by an etching gas containing β-diketone containing at least one of water and alcohol is etched at a substrate temperature of 300 ° C. or higher, preferably 450 ° C. or higher. Further, an etching method including an etching step for exposing the surface of the substrate is described. Further, Patent Document 2 describes a complex of β-diketone and a metal in a temperature range of 100 ° C. or higher and 350 ° C. or lower using an etching gas containing β-diketone and containing 1 to 20% by volume of water or hydrogen peroxide. A method of etching a metal film by forming a metal film is described. In Patent Document 2, zinc, cobalt, hafnium, iron, manganese, vanadium and the like are mentioned as examples of the metal constituting the metal film. According to Patent Document 2, by adding water or hydrogen peroxide, the speed of etching the metal film becomes faster than that in the case of using oxygen.

Further, although it is not a method of finely etching the metal film on the substrate, a method of using β-diketone is proposed as a method of dry cleaning the metal film adhering to the film forming apparatus used in the manufacturing process of the semiconductor device. Has been done.

For example, Patent Document 3 describes a metal film containing a cleaning gas containing β-diketone and NO _x (any of NO and N2O) in a temperature range of ₂₀₀ to 400 ° C, preferably 250 to 370 ° C. A dry cleaning method for removing the metal film adhering to the film forming apparatus by reacting with the above is described. In Patent Document 3, nickel, manganese, iron, cobalt and the like are mentioned as examples of the metal constituting the metal film. According to Patent Document 3, the use of NO _x widens the temperature range in which the metal film can be removed by etching as compared with the case of using oxygen.

Japanese Unexamined Patent Publication No. 2004-91829 Japanese Unexamined Patent Publication No. 2014-236906 Japanese Unexamined Patent Publication No. 2013-194307

It is conceivable to use the cleaning gas containing β-diketone and NO _x (any of NO and N2O) described in Patent Document ₃ as the etching gas for the metal film. However, as a result of the study by the present inventor, when β-diketone gas is supplied to the substrate and the metal film is etched, the β-diketone is decomposed by the catalytic effect of the metal, and carbon is mainly contained in the treated substrate. In some cases, the film as a component (hereinafter referred to as carbon film) remains, or in some cases, the structure of the semiconductor device to be treated is damaged. The present inventors have found that when NO _x gas is used as an additive gas, the formation of a carbon film and damage to the object to be processed can be suppressed by lowering the temperature of the substrate during etching, but at the same time, the metal film can be suppressed. There was a problem that the etching rate of the above was also lowered.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method capable of improving the etching speed of a metal film.

The present inventors have found that when etching a metal film using β-diketone, the etching rate is increased by adding not only oxidizing gas such as NO but also water and the like, and the present invention has been made. It came to.

The etching method of the present invention is a dry etching method in which an etching gas is brought into contact with a metal film on a substrate in a temperature range of 100 ° C. or higher and 350 ° C. or lower, and the etching gas is β-diketone and the first. The metal film contains an added gas and a second added gas, the metal film contains a metal element capable of forming a complex with the β-diketone, and the _first added gas is composed of NO, N2O _{, O2} and O3. The β- which is at least one gas selected from the group and the second added gas is at least one gas selected from the group consisting of H ₂ O and H ₂ O ₂ and is contained in the etching gas. The amount of the diketone is 10% by volume or more and 90% by volume or less with respect to the etching gas, and the amount of the second added gas contained in the etching gas is 0.1% by volume or more and 15% by volume with respect to the etching gas. It is characterized by the following.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method capable of improving the etching rate of a metal film.

The schematic diagram of the etching apparatus which concerns on one Embodiment of this invention. The sectional view of the filled container which concerns on one Embodiment of this invention. The graph which shows the relationship between the water content in the etching gas and the etching rate in an Example / comparative example.

Hereinafter, embodiments of the present invention will be specifically described.
However, the present invention is not limited to the following embodiments, and can be appropriately modified and applied without changing the gist of the present invention.

(Etching method for metal film)
The present invention is a dry etching method in which a metal film on a substrate is etched using an etching gas. The etching gas includes β-diketone, a first additive gas, and a second additive gas, and the metal film is β. -A dry etching method characterized by containing a metal element capable of forming a complex with a diketone.

In the present invention, when an etching gas is introduced into an etching apparatus in which an object to be processed containing a metal film is arranged and the etching gas is brought into contact with the metal film of the object to be processed in a heated state, β-
The diketone and the metal atom form a metal complex. Since this metal complex has a high vapor pressure, the metal film can be removed by vaporizing the metal complex. The present invention is characterized in that the etching rate of the metal film is increased by including the first additive gas and the second additive gas in the etching gas.

In the present invention, the first additive gas having an oxidizing property oxidizes the metal film, and further, the second additive gas capable of combining β-diketone and the metal atom constituting the metal film to form a metal complex is added. , It is considered that the etching speed will be increased.

In the present invention, the etching rate is measured by measuring the film thickness per unit time from the difference (weight change) between the weight of the object to be etched after etching and the weight of the object to be processed before treatment and the specific gravity of the metal film. The method of determining the amount of decrease (nm / min) was used.

The metal film to be the target of the dry etching method of the present invention is formed of a metal element capable of forming a complex with β-diketone. Specifically, at least one element selected from the group consisting of Co, Fe, Ni, Zn, Hf, V and Cu can be mentioned. The metal film may be not only a film composed of any one of the above elements but also a metal film composed of a plurality of elements. For example, metals such as NiSi, CoSi, HfSi, NiCo, FeCo, CoPt, MnZn, NiZn, CuZn, FeNi, and oxide films thereof can be mentioned. Above all, the present invention is effective for a metal film containing Co. In the present invention, a known semiconductor substrate, glass substrate, or the like can be used as the substrate.

The first added gas is at least _one gas selected from the group consisting of NO, N2O _{, O2} and O3. The second added gas is at least one gas selected from the group consisting of H ₂ O and H ₂ O ₂ .

Examples of the β-diketone used in the present invention include hexafluoroacetylacetone, trifluoroacetylacetone, acetylacetone and the like, and not only one type but also two or more types can be used. In particular, hexafluoroacetylacetone and trifluoroacetylacetone are suitable because they can be etched at high speed. The etching rate of the metal film increases as the concentration of β-diketone contained in the etching gas increases. However, when the vapor pressure of β-diketone is low and there is a concern that liquefaction may occur in the film forming apparatus, it is preferable to adjust the concentration appropriately with a diluting gas.

The content of β-diketone contained in the etching gas is preferably 10% by volume or more and 90% by volume or less, preferably 30% by volume or more and 60% by volume or less, in the etching gas composition from the viewpoint of obtaining a sufficient etching rate. The following is more preferable.

The content of the first added gas contained in the etching gas is preferably 0.01% by volume or more and 10% by volume or less in the etching gas composition from the viewpoint of obtaining a sufficient etching rate, and is preferably 0.05 volume by volume. It is more preferably% or more and 8% by volume or less, and further preferably 0.1% by volume or more and 5% by volume or less.

The content of the second added gas contained in the etching gas is preferably 0.1% by volume or more and 15% by volume or less, preferably 0.5% by volume or more and 10% by volume or less in the etching gas composition. It is more preferably 2% by volume or more and 8% by volume or less. The ratio of the second added gas contained in the etching gas to β-diketone is preferably 0.5% by volume or more and 50% by volume or less, and more preferably 1% by volume or more and 20% by volume or less. ..

Further, in addition to the β-diketone, the first added gas, and the second added gas, an inert gas such as _N2 , He, Ar, Ne, or Kr can be added to the etching gas. When an inert gas is added, the concentration is not limited if it is diluted to an appropriate concentration and used, but in the etching gas composition, it is usually 1% by volume or more and 90% by volume or less, preferably 10% by volume. It is used at a content of 80% by volume or more, more preferably 30% by volume or more and 50% by volume or less.

(Etching device)
The dry etching method of the present invention can be realized, for example, by using a general etching apparatus used in the semiconductor manufacturing process as shown in FIG. In one embodiment, the etching apparatus 100 according to the present invention includes, for example, a processing container 110 on which a substrate (processed object 112) on which a metal film containing a metal element capable of forming a complex with β-diketone is formed is arranged. The β-diketone supply unit 130 connected to the processing container 110 to supply β-diketone, the first added gas supply unit 140 to supply the first added gas, and the second added gas supply unit to supply the second added gas. The unit 150 includes an inert gas supply unit 160 for supplying the inert gas, and a heating means 170 for heating the processing container 110. The gas flow rate control unit (not shown) is connected to the β-diketone supply unit 130, the first added gas supply unit 140, the second added gas supply unit 150, etc., and supplies the β-diketone and the like to the object to be processed 112. The control signal of the valve is output as such.

The processing container 110 includes a mounting portion 111 for arranging the object to be processed 112. The processing container 110 is not particularly limited as long as it is resistant to the β-diketone used and can be depressurized to a predetermined pressure, but is usually a general processing container provided in a semiconductor etching apparatus or the like. Is applied. Further, the supply pipe for supplying the etching gas and other pipes are not particularly limited as long as they are resistant to β-diketone, and general pipes can be used.

The β-diketone supply unit 130 is connected to the processing container 110. The β-diketone supply unit 130 supplies the β-diketone to the processing container 110 via the pipe 121. In FIG. 1, the supply amount of β-diketone is adjusted by the valve 135 and the flow rate adjusting means 133, and is supplied from the pipe 131 to the pipe 121. Further, the inert gas as the diluting gas is supplied from the inert gas supply unit 160 to the pipe 121 from the pipe 161 after the supply amount is adjusted by the valve 165 and the flow rate adjusting means 163. Further, the first added gas supply unit 140 adjusts the supply amount by the valve 145 and the flow rate adjusting means 143, and supplies the first added gas from the pipe 141 to the pipe 121. Further, the second added gas supply unit 150 adjusts the supply amount by the valve 155 and the flow rate adjusting means 153, and supplies the second added gas from the pipe 151 to the pipe 121.

In the etching apparatus 100, the β-diketone is diluted to a predetermined concentration by the inert gas supplied from the inert gas supply unit 160, and the first added gas and the second added gas supplied from the first added gas supply unit 140. It is preferable that the gas is supplied to the processing container 110 in a state of being mixed with the second additive gas supplied from the gas supply unit 150 at a predetermined concentration. However, the β-diketone does not have to be diluted with the inert gas.

A heating means 170 for heating the processing container 110 is disposed outside the processing container 110. Further, a heater (not shown) may be provided inside the mounting portion 111 as a second heating means. When a plurality of mounting portions are arranged in the processing container 110, each mounting portion may be individually set to a predetermined temperature by providing a heater for each mounting portion.

One of the processing containers 110 is provided with a gas discharging means for discharging the gas after the reaction. The vacuum pump 173 of the gas discharge means discharges the reaction gas from the processing container 110 via the pipe 171a. The gas after the reaction is recovered by a liquid nitrogen trap 175 arranged between the pipes 171a and 171b. Valves 177a and 177b can be arranged in the pipes 171a and 171b to adjust the pressure. Further, in FIG. 1, PI 123 and 125 are pressure gauges, and the control unit can control each flow rate adjusting means and each valve based on the indicated value.

The etching method will be specifically described by taking the etching apparatus 100 as an example. A base material (processed body 112) on which a metal film containing a metal element capable of forming a complex with β-diketone is formed is arranged. The inside of the processing container 110, the pipe 121, the pipe 131, the pipe 141, the pipe 151, the pipe 161 and the liquid nitrogen trap 175, the pipes 171a and 171b are vacuum-replaced to a predetermined pressure by the vacuum pump 173, and then covered by the heating means 170. The treated body 112 is heated. When the predetermined temperature is reached, β-diketone, the first added gas and the second addition are made from the β-diketone supply unit 130, the first added gas supply unit 140, the second added gas supply unit 150 and the inert gas supply unit 160. The gas and the diluting gas are supplied to the pipe 121 at a predetermined flow rate.

The diluted β-diketone and the additive are mixed in a predetermined composition and supplied to the processing container 110. While introducing the mixed etching gas into the processing container 110, the inside of the processing container 110 is controlled to a predetermined pressure. The metal film is etched by reacting the etching gas with the metal film for a predetermined time. In the present invention, etching is possible without plasma, and it is not necessary to excite the etching gas with plasma or the like at the time of etching.

After the etching is completed, the heating by the heating means 170 is stopped to lower the temperature, and the vacuum pump 173 is stopped to release the vacuum. As described above, the metal film according to the present invention can be etched.

(Etching conditions)
Next, in the etching method of the present invention, the temperature at the time of etching may be any temperature as long as the complex can be vaporized, and in particular, the temperature of the metal film to be removed is preferably 100 ° C. or higher and 350 ° C. or lower. , 150 ° C. or higher and lower than 250 ° C. is more preferable. The pressure in the processing container during etching is not particularly limited, but is usually in the pressure range of 0.1 kPa or more and 101.3 kPa or less.

When the metal film to be removed contains cobalt, the β-diketone is hexafluoroacetylacetone, and the added gas is nitric oxide, etching at a high temperature of about 300 to 400 ° C. decomposes hexafluoroacetylacetone. Since a carbon film may be formed or the structure of the element may be damaged, it is preferable that the object to be treated is heated to 150 ° C. or higher and lower than 250 ° C., and to be heated to 200 ° C. or higher and lower than 250 ° C. Is more preferable, and it is further preferable to heat the temperature to 220 ° C. or higher and lower than 250 ° C. Within the above temperature range, the pressure in the processing vessel is preferably 20 Torr or more and 300 Torr or less (2.67 kPa or more and 39.9 kPa or less), and 50 Torr or more and 250 Torr or less (6) from the viewpoint of obtaining a sufficient etching rate. It is more preferably .67 kPa or more and 33.3 kPa or less), and further preferably 100 Torr or more and 200 Torr or less (13.3 kPa or more and 26.7 kPa or less).

The etching time is not particularly limited, but is preferably 60 minutes or less in consideration of the efficiency of the semiconductor device manufacturing process. Here, the etching time means that the etching gas is introduced into the processing container in which the substrate is installed inside the etching process, and then the etching gas in the processing container is vacuum pumped to finish the etching process. It refers to the time until exhausting due to etching.

(Pretreatment of the object to be processed)
If necessary, pretreatment of the object to be processed may be performed. For example, when the metal film to be removed contains cobalt, the variation in the etching rate due to the thickness of the natural oxide film can be improved by reducing the cobalt natural oxide film.

Pretreatment can be performed by supplying the reducing gas to the object to be treated 112 from the reducing gas supply unit (not shown).

In the reducing gas supply step, the reducing gas is not limited to hydrogen gas, and for example, a gas such as carbon monoxide (CO) or formaldehyde (HCHO) can be used.

In the reducing gas supply step, only the reducing gas such as hydrogen gas may be supplied, but it is preferable that the reducing gas is diluted with a diluting gas such as nitrogen gas.

Further, in the reducing gas supply step, it is preferable that β-diketone and nitric oxide gas are not supplied. Specifically, the ratio of the amounts of β-diketone and nitrogen monoxide gas to the total amount of gas supplied in the reducing gas supply step is preferably less than 0.01% by volume and 0.001% by volume, respectively. It is more preferably less than%, and particularly preferably 0% by volume.

The treatment temperature of the reducing gas supply step is not particularly limited as long as it is a temperature at which the natural oxide film can be reduced, but if the treatment temperature of the reducing gas supply step is low, the reduction reaction hardly proceeds. Further, although the processing temperature in the reducing gas supply step may be high, it is preferable that the processing temperature is the same as the processing temperature in the first mixed gas supply step in terms of operation of the etching apparatus.
From the above, in the reducing gas supply step, the object to be treated is preferably heated to 100 ° C. or higher and 350 ° C. or lower, more preferably 150 ° C. or higher and 250 ° C. or lower, and 200 ° C. or higher and 250 ° C. or lower. It is more preferable to be heated.

In the reducing gas supply step, the flow rate of the reducing gas depends on the volume of the processing container. In the reducing gas supply step, the pressure in the processing container is not particularly limited, but may be appropriately set in the range of, for example, 10 to 500 Torr (1.33 to 66.5 kPa) according to the apparatus.

The processing time of the reducing gas supply step may be appropriately adjusted according to the method of forming the metal film formed on the substrate and the like.

(Filled container)
As the β-diketone supply unit 130 of the present invention, a β-diketone-filled container 200 in which β-diketone is filled in a closed container 201 as shown in FIG. 2 can be used. The β-diketone-filled container 200 is obtained by filling a closed container 201 with a liquid β-diketone, and the β-diketone is divided into a liquid phase 213 and a gas phase 211 in the closed container 201. The closed container 201 is provided with an outlet 203 capable of filling and taking out the β-diketone, and can supply the β-diketone of the gas phase 211 in a gas state. When supplying the gas-state β-diketone from the β-diketone-filled container 200, it is necessary to heat the β-diketone-filled container 200 to supplement the volatile heat of the β-diketone in the liquid phase 213.

The β-diketone content (purity) in the liquid β-diketone filled in the closed container 201 is preferably 99% by mass or more, more preferably 99.5% by mass or more, and 99.9% by mass or more. More preferred. The β-diketone content (purity) in the liquid β-diketone can be measured by gas chromatography.

(Semiconductor device)
The etching method according to the present invention can be used as an etching method for forming a predetermined pattern on a metal film of a conventional semiconductor device. The semiconductor device according to the present invention can be manufactured at low cost by using a metal film etched by the etching method according to the present invention. Examples of such semiconductor devices include solar cells, hard disk drives, dynamic random access memory, phase change type memory, ferroelectric memory, magnetoresistive memory, resistance change type memory, MEMS and the like.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to such examples. In the etching test of the metal film, the relationship between the water content in the etching gas and the etching rate was investigated.

First, hexafluoroacetylacetone (HFAc) in a liquid state having a purity of 99.9% by mass or more was filled in a closed container to obtain a container filled with β-diketone.

As the etching apparatus, a cobalt foil (shape 2 cm × 2 cm, thickness 0.1 mm) was used as the object to be processed 112 according to the etching apparatus 100 shown in FIG. In addition, the above-mentioned β-diketone-filled container was used for the β-diketone supply device.

After vacuum replacing the inside of the processing container 110 and the pipe 121, the pipe 131, the pipe 141, the pipe 151, the pipe 161 and the liquid nitrogen trap 175, and the pipes 171a and 171b to less than 10 Pa, they are arranged inside the heating means 170 and the mounting portion 111. The weight-measured object to be processed, which was placed on the mounting portion 111, was heated by the provided heater. After confirming that the heater arranged inside the heating means 170 and the mounting portion 111 has reached 220 ° C., hydrogen gas 10 sccm is supplied from a hydrogen gas supply unit (not shown) at a pressure of 50 Torr for 5 minutes, which is a pretreatment. A gas supply process was performed. After the vacuum is replaced to less than 10 Pa again after the pretreatment is completed, the etching gas is supplied into the processing container 110 by supplying β-diketone, the first added gas, the second added gas and the inert gas to the pipe 121 at a predetermined flow rate. The inside of the processing container 110 was controlled to a predetermined pressure while being introduced into. After a predetermined time has elapsed from the start of the introduction, the introduction of the etching gas is stopped, the inside of the processing container 110 is opened to vacuum, the object to be processed is taken out and the weight is measured, and the weight is measured based on the weight change of the object to be processed before and after the test. The etching rate was calculated from the amount of decrease in thickness and the etching time.

In the etching test of this example, the temperature of the object to be treated is 220 ° C., the total amount of etching gas to be introduced is 100 sccm, the first added gas is NO, the second added gas is H ₂ O, the diluted gas is N ₂ , and the pressure is. The etching time was 2.5 minutes at 100 Torr.

Table 1 shows the etching rates of each etching condition in Examples and Comparative Examples. Further, FIG. 3 shows the relationship between the water content in the etching gas and the etching rate.

From FIG. 3, in Examples 1 to 6 in which the second added gas was added to the etching gas, the etching rate was 21 nm / min or more, which was about twice or more the etching rate of Comparative Example 1 in which the second added gas was not added. It has risen. In particular, in Examples 3 to 5 in which the water content was 2 to 8% by volume, the etching rate was particularly high. In each Example and Comparative Example, the formation of a carbon film was not confirmed because the temperature of the object to be treated was as low as 220 ° C.

100 Etching device 110 Processing container 111 Mounting unit 112 Processed object 121 Piping 130 β-Diketone supply unit 131 Piping 133 Flow adjustment means 135 Valve 140 First additive gas supply unit 141 Piping 143 Flow adjustment means 145 Valve 150 Second additive gas Supply unit 151 Piping 153 Flow adjustment means 155 Valve 160 Inactive gas supply unit 161 Piping 163 Flow adjustment means 165 Valve 170 Heating means 171a, b Piping 173 Vacuum pump 175 Liquid nitrogen trap 177a, b Valve 200 β-diketone filled container 201 Closed container 203 Outlet 211 Gas phase 213 Liquid phase

Claims (14)

A dry etching method in which an etching gas is brought into contact with a metal film on a substrate in a temperature range of 100 ° C. or higher and 350 ° C. or lower to perform etching.
The etching gas contains β-diketone, a first additive gas and a second additive gas, and contains
The metal film contains a metal element capable of forming a complex with the β-diketone.
The _first added gas is at least one gas selected from the group consisting of NO, N2O _{, O2} and O3.
The second added gas is at least one gas selected from the group consisting of H ₂ O and H ₂ O ₂ .
The amount of the β-diketone contained in the etching gas is 10% by volume or more and 90% by volume or less with respect to the etching gas.
The amount of the second added gas contained in the etching gas is 0.1% by volume or more and 15% by volume or less with respect to the etching gas.
A dry etching method comprising a pretreatment step of supplying a reducing gas to a metal film on a substrate before the etching. The dry etching method according to claim 1, wherein the etching gas is brought into contact with the metal film in a temperature region of 150 ° C. or higher and lower than 250 ° C. The dry etching method according to claim 1 or 2, wherein the amount of the second added gas contained in the etching gas is 0.5% by volume or more and 10% by volume or less with respect to the etching gas. The dry etching method according to claim 3, wherein the amount of the second added gas contained in the etching gas is 2% by volume or more and 8% by volume or less with respect to the etching gas. Claims 1 to 4 are characterized in that the amount of the second added gas contained in the etching gas is 0.5% by volume or more and 50% by volume or less with respect to the β-diketone contained in the etching gas. The dry etching method according to any one of the above items. The invention according to any one of claims 1 to 5, wherein the amount of the first added gas contained in the etching gas is 0.01% by volume or more and 10% by volume or less with respect to the etching gas. Dry etching method. The invention according to any one of claims 1 to 6, wherein the metal element is at least one metal element selected from the group consisting of Co, Fe, Ni, Zn, Hf, V and Cu. Dry etching method. The dry etching method according to any one of claims 1 to 7, wherein the β-diketone is at least one compound selected from the group consisting of hexafluoroacetylacetone, trifluoroacetylacetone and acetylacetone. The metal film contains cobalt, and the etching gas contains hexafluoroacetylacetone as a β-diketone, NO as the first added gas, and _H2O as the second added gas.
The amount of _H2O gas contained in the etching gas is 0.5% by volume or more and 10% by volume or less with respect to the etching gas.
The dry etching method according to claim 1, wherein the etching gas is brought into contact with the metal film in a temperature region of 150 ° C. or higher and lower than 250 ° C. Further, according to any one of claims 1 to 9, the etching gas contains at least one inert gas selected from the group consisting of N ₂ , Ar, He, Ne and Kr. Dry etching method. The reducing gas includes hydrogen gas, carbon monoxide gas, and formaldehyde gas.
The dry etching method according to any one of claims 1 to 10, wherein the flow rate of the reducing gas is controlled so that the pressure in the processing container in the pretreatment step is in the range of 1.33 to 66.5 kPa. .. A method for manufacturing a semiconductor device, comprising a step of etching a metal film on a substrate by the dry etching method according to any one of claims 1 to 11. A mounting portion provided in a heatable treatment container and on which a material to be treated having a metal film formed on the surface is placed,
The β-diketone supply unit that supplies the β-diketone to the object to be treated,
A first added gas supply unit that supplies the first added gas, which is at least one gas selected from the group consisting of NO, N ₂ O, O ₂ and O ₃ , to the object to be treated, and the first added gas supply unit.
A second additive gas supply unit that supplies a second additive gas, which is at least one gas selected from the group consisting of H ₂ O and H ₂ O ₂ , to the object to be treated, and a second additive gas supply unit.
The amount of the β-diketone, the first added gas and the second added gas is 10% by volume, respectively, with respect to the total amount of the β-diketone and the second added gas to be supplied to the object to be treated. A control unit that outputs a control signal to supply the object to be processed heated to a temperature range of 100 ° C. or higher and 350 ° C. or lower so as to be 90% by volume or less and 0.1% by volume or more and 15% by volume or less. ,
A reducing gas supply unit for supplying the reducing gas to the object to be treated is provided .
The control unit outputs a valve control signal so as to supply the reducing gas to the object to be processed before supplying the β-diketone and the first and second added gases to the object to be processed. Etching device characterized by that. The reducing gas includes hydrogen gas, carbon monoxide gas, and formaldehyde gas.
The etching apparatus according to claim 13, wherein the flow rate of the reducing gas is controlled so that the pressure in the processing container in the pretreatment step is in the range of 1.33 to 66.5 kPa.

Images